Confirmation of distemper in two wild Siberian tigers is bringing new attention to infectious disease threats to the endangered species.
Courtesy of the U.S. Fish and Wildlife Service
posted November 16, 2011
Russian and Wildlife Conservation Society veterinarians have teamed up to determine how serious a threat distemper is to endangered Siberian tigers.
Using a combination of histologic examination, PCR assays, and DNA sequencing at the WCS's Wildlife Health Center at the Bronx Zoo, the team characterized distemper infections in two wild Siberian tigers from the Russian Far East.
The diagnosis is a much-anticipated confirmation that wild tigers have been infected with the distemper virus, which the WCS and Russian veterinarians first documented in 2003.
The team, which includes veterinarians from the Primorskaya State Agricultural Academy and the Moscow Zoo, presented its findings this September at the first Russian symposium on wildlife diseases, in the city of Ussurisk.
In 2010, a gaunt female tiger with neurologic signs was shot dead when the animal wandered into a Russian village. A similar event occurred seven years earlier. In that instance, WCS staff immobilized the tiger, which later died in captivity.
Samples collected from the tigers were tested to make the distemper diagnosis. Whether the tigers contracted distemper from a wild animal or domestic dog, both of which are reservoirs for the virus, is not known.
Dr. Denise McAloose, the WCS's chief pathologist and lead investigator of the tiger study, noted the benefits of international collaboration in making the diagnosis. "Without our Russian associates there on the spot, knowing what samples to collect and how to preserve these specimens, samples would never have made it to our lab, and the cause of death would remain unknown."
Recent years have seen a disturbing uptick in reports of unusual behavior in wild Siberian tigers, ranging from tigers entering villages to stalling traffic on major roadways—behavior possibly indicative of distemper infection.
Conservation organizations estimate as few as 3,200 Siberian, or Amur, tigers remain in the wild. The endangered animals are already in jeopardy as a result of poaching and habit loss, but now they may face a new threat.
"With all the threats facing Siberian tigers from poaching and habitat loss, relatively little research has been done on diseases that may afflict tigers," said Dale Miquelle, director of Russia Programs for the WCS. "There are no records of tigers entering villages and behaving so abnormally before 2000, so this appears to be a new development and new threat."
"Understanding whether disease is a major source of mortality for Siberian tigers is crucial for future conservation efforts," Miquelle added.
Dr. Irina Korotkova of the Prim-orskaya State Agricultural Academy says the East-West collaboration provides a foundation for elucidating potential disease threats to tigers in the Russian Far East. "Understanding the role of distemper in our wild Amur tiger population is vitally important," Dr. Korotkova said.
Currently, the WCS is working with the Agriculture Academy in Primorskaya and others to establish a wildlife diagnostic laboratory in Ussurisk, although the facility is not expected to be adequately funded and fully functional for several years.
"Until then, there's still much to do, including identifying the source of the disease," Dr. McAloose said.